• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.168-177
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• 1997

This study was carried out to find the physico-chemical properties of soils and the rice growth at the pilot project rice farm of Buchanan city, Liberia. The results were as follows. Soils were classified as Plinthic Ferralsols. Real tropical soils had an oxic B horizon of 30cm thick with diffused horizon boundaries. The surface soils have Ochric A horizon with low organic matter. Plinthite was distributed throughout the whole soil profile unevenly. Exposed to sun light, Plinthite was dried out, hardened, and developed irreversibly into ironstone. There were 286 termite hills in 20ha in the project area. The pH value of the termite hills was higher than that of the ordinary soil two units. Soils of the termite hills had higher contents of carbon, nitrogen, available phosphate and exchangeable bases, especially calcium(2,000mg/kg). Available Fe contents was 230~330mg/kg in the surface soil, and 2,200mg/kg in the subsoil. This caused bronzing of rice in a few days after transplanting. The tolerance of Fe toxicity was lower in Korean cultivars than in Liberian cultivars. The tolerant cultivar was Hangang among Korean cultivars and Nizersail and Suakoko 8 among Liberian cultivars. Area weighted average percolation rate was 8.3mm/day and infiltration rate was 2~2.5mm/hr.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.114-121
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• 1997

Latex Coated Urea(LCU) was compared with ordinary urea under different methods of application in terms of N use efficiency and yield of rice, 1995 and 1996. The study was carried out on Jeonbug silty clay loam, in Honam Agricultural Experiment Station. The fertilizer treatments involved (1) conventional application of urea (44kg N/ha at transplanting, 33kg N/ha at five leaves stage, 33kg N/ha. (4) 55kg N/ha at transplanting and 33kg N/ha as urea at panicle initiation stage, and (5) without N. It was found that by combining LCU(as basal application) and urea(as topdressing at panicle initiation stage), at the rate of 80% of conventional rate with ordinary urea is most effective for the saving of N and increasing the use efficiency of N by rice. It was, however, observed that the efficacy of LCU was affected by the temperature during the growth of rice.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.7-14
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• 2004

This study was conducted to investigate the effect on agricultural environment and crop productivity by different amount of applied fertilizer in consideration of irrigation water quality. N, P and K contents of irrigation water used in this experiment were 6.16, 0.26 and 9.37 mg/L, respectively. N, P and K Concentrations of runoff water were lower than those of inflow water during rice cultivation. N, P and K Concentrations of ponded and percolated water were changed according to the amount and time of applied fertilization. During rice cultivation in paddy soil, nitrogen balance was closed to 0 in SFT 50% (50% level of soil testing fertilization), 0.14 kg/ha, but it was 95.3 kg/ha in CF (conventional fertilization) treatment In SW 50% and STF (soil testing fertilization) treatment yield of perfect rice was not greatly different as compared with CF treatment due to the superiority of ripening rate, 1,000 grains weight and milling characteristics. Mechanical paratability of rice was excellent in NF (non fertilization) treatment, STF 50% treatment showed higher in nutrient availability and fertilizers use efficiency than other treatments.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.3
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• pp.155-161
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• 1974

In order to investigate the effect of split application of silicate fertilizers on the rice plant, this studies, designed with two kinds of silicate material, wollastonite and high concentrated fused silicate material, and 4 types of application dates on the pot experiment without chemical control against diseases, have conducted the silica analysis of rice plant and diseased rates of plant during the all growing stages. The silica contents in rice plant with basal application were increased most highly compared with the split applications during the all growing stage, but they were all much the same between the basal and split application at the harvest. High concentrated fused silicate material was more useful to increase the silica content in rice plant than wollastonite and effect of split application of silica was dominant with this fused silicate material. The diseased leaf area by rice blast was decreased from the 50% of uncontrolled plot to 20~40% by the split application with wollastonite and to 5~15% with high concentrated fused silicate material. Also percents of deseased panicles were decreased to 20% with wollastonite and to 10% with high concentrated fused silicate material.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.4
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• pp.201-209
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• 1982

In 1980, the abnormal low temperature was lasted during the late stage of rice growing season, thus low temperature injury occurred severely. The severity of the injury and nutrition absorption were investigated. The result obtained were summarized as follows: 1. It was considered that the severe low temperature injury of rice was caused by the low temperature and shorts of sunshine in the late growing season of rice, especially, the minimum air temperature which was lasted for a few days below critical reproductive growing temperature in the meiosis stage affected high the injury. 2. The low tmperature injury was lightened in the no nitrogen applied plot, and becoming severe with high nitrogen levels, but the balanced application of NPK lessened the low temperature injury. 3. The low temperature injury was more severe in Indica and Japonica hybrid than in Japonica cultivar, and the injury was shown as sterilizing, degraded spiklets, ill emerging of head and inhibition of nutrition absorption, etc. 4. Under the low temperature condition, $SiO_2$ content of rice plant was significantly reduced according to the increase of nitrogen levels. 5. Under the low temperature condition, the optimum application amount of nitrogen for Milyang 23, was 13, 6 kg/10a, this was approximately 10kg/10a smaller than average in usual year. The highly reduced rice yield was resulted from the cool injury, and the reducing rate of yield was larger in Indica and Japonica hybrid cultivar than in Japonica cultivar.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.278-288
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• 1995

Weed species occurred in dry- and water-seeded rice were 14 (2 grasses, 8 broadleaves, and 4 sedges) and 12 species (1 grasses, 7 broadleaves, and 4 sedges), respectively. Dominant weed species in dry-seeded rice were Lindernia procumbens, Cyperus difformis, Cardamine flexuosa, and Cyperus serotinus in discending order. The species in water-seeded rice were Cyperus difformis, Scirpus juncoides, and Lindernia procumbens. The number of weed species emerged in direct-seeded rice was determined at about 45 days after seeding, and dry weights of weeds were increased up to 75~90 days after seeding. Timing for great increase of plant height varied depending upon weed species. Regardless of weed number emerged, the most dominant weeds until late stage of growth were Cyperus difformis, Bidens frondosa, Digitaria ciliaris and Echinochloa crus-galli in dry- seeded rice, and Cyperus difformis, Echinochloa eras-galli and Scirpus juncoides in water-seeded rice.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.3
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• pp.176-182
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• 2020

National Institute of crop Science of the Rural Development Administration (RDA) has conducted long-term monitoring studies to find out the relationship between crop yield and climatic factors for major food crops including rice. Rice growth and y ield have been monitored in 17 regions where the branches of the National Institute of Crop science and the Provincial Agricultural Research and Extension Service locate. The data obtained from monitoring studies for rice growth and yield include the observation of vegetative growth status and yield components, which include leaf number, biomass and the weight of 1000 grains. These data have been collected from rice fields where standard management procedures have been applied. The observation data for crop growth and yield monitoring studies from 1999 to 2019 are open to public through agricultural science library operated by RDA.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.56 no.1
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• pp.44-49
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• 2011

The bio-degradable transplanting pot containing rice by-product (rice-hull and rice-bran) were developed, and tested their ability for agronomic use. Rice by-products were crosslinked with biodegradable aliphatic ally aromatic copolyesters or urea resin for making transplanting pot. Mechanical properties and degradability of these pots were measured and compared to those of the Jiffy pot (commercially used bio-degradable pot). Mechanical strength was higher than that of Jippy pot, and bio-degradability was excellent under the actual field condition. In addition, the pot could be degraded within 3 months under the ground. Our result indicated bio-degradable pot containing rice by-products has a great potential for such agronomic use.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.155-165
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• 1992

Experiments were conducted to determined the development of the vascular bundles in the peduncle of different tillers on its development in order to improve the vascular system and possibly increase grain yield. The development of the vascular bundle in the leaf, stem and panicle is an important aspect of assimilate translocation and differentiation of panicle characters. Two cultivars were used in this study: IR58, an indica type, and Unbong 7, a japonica type. The main culm(M) had more and bigger vascular bundles in the peduncle and those vascular bundle decreased with tiller order and tiller development. In the primary tillers, P1 had more large and small vascular bundles than P5 in both cultivars. IR58 developed more large vascular bundles compared to Unbong 7, but the small vascular bundle in unbong 7 was more than in IR58. The cross sectional area of phloem and xylem in large vascular bundle decreased with tiller order in both cultivar. Larger area of phloem and xylem in the early formed tillers more efficient transport of assimilates. The number of spikelets, the weight of panicle and grain yield per panicle were highest in the main culm followed by the order of their initiation or emergence. The number of primary and secondary branches to be positive associated with the number and area of vascular bundles. Furthermore, the number of vascular bundles in the peduncle was highly correlated with the peduncle thickness which in turn was correlated with the number of primary and secondary branches on the panicle. These results showed tillers that are initiated early and have relatively ation usually have more vascular bundles, larger peduncle, more spikelets spike let filling and ultimately higher yield.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.6
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• pp.499-505
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• 1992

This experiment was carried out to find out the optimum application method of slow-release fertilizer under different soil textures, clay loam(Deogpyeong series), sandy loam (Gangseo series) in the southern region(Milyang, Kyeongnam) of Korea. The fertilizers used were Chosun slow-release fertilizer(silicate latex coated fertilizer: N-P$_2$O$_{5}$-K$_2$O=18-12-13) and Meister 15 (thermoplastic resin coated fertilizer : N-P$_2$O$_{5}$-K$_2$O=14-14-14). The two whole basal application methods such as side band placement at transplanting time of rice plant(cv.Donghaebyeo) and incorporation with soil as basal were tested. The released amount of ammonium nitrogen from the soils for 4 days submerged was 95ppm in sandy loam and 60ppm in clay loam. The greenish degree of rice leaf was higher at the whole plow layer placement method than the others. The nitrogen efficiencies of the fertilizers were Meister 15 > convention > Chosun in order and between the application methods were similiar. The growth status was better at the whole plow layer placement application method of Meister 15 regardless of soils and seedling ages. The ripening ratio was increased at slow-release fertilizer application, and between application methods, whole plow layer placement was lower because of lodging damage. The yield in clay loam soil showed a significant difference between the ferilizers, but there were slight differences between the application methods and fertilizers in sandy loam soil. As a result, the slow-release fertilizer, Meister 15, applied at the whole layer showed a good rice growth and seemed a plausible fertilizing method.